1. Field of the Invention
This invention relates to optoelectronic connector assembly systems and, in particular, to electrical connector parts for housing optoelectronic transducers and to optical connector parts for housing terminal portions of a fiber optic light guide. The invention also relates to a fiber optic light guide having an integral lens associated therewith. Accordingly, the general objects of this invention are to provide new and improved systems, parts, and combined guide-lens of such character.
2. Description of the Prior Art
For certain applications, it is desirable to transmit signals between two stations of a system over a closed, nonconductive, nonelectrical transmission path. Such a path can employ a flexible fiber optic light guide. Electrical signals are converted to light signals at one end of the system, and the light signals are transmitted by way of the fiber optic light guide to the other end of the system where they are reconverted into electrical signals. Thus, the two ends of the system can be electrically isolated from each other; electrical interference does not affect the signals conducted over the optical transmission path.
Various techniques have been employed in the past for such transmission. The following references may be helpful for a delineation of the scope of such prior art techniques. They include the following United States Patents:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 3,517,981 Rueger et al. June 30, 1970 3,637,284 Plyler June 25, 1972 3,789,485 Gudnestad Feb. 5, 1974 3,790,791 Anderson Feb. 5, 1974 3,790,923 Mathe Feb. 5, 1974 3,792,284 Kaelin Feb. 12, 1974 3,809,908 Clanton May 7, 1974 3,846,010 Love Nov. 5, 1974 ______________________________________
Also of interest is a publication titled "Designing with Du Pont Crofon Fiber Optics" by the Du Pont Company, including a designation A-76182.
Rueger et al., U.S. Pat. No. 3,517,981, relates to termination members for fiber optic means. Fiber members of a fiber optic bundle are crimped by a termination member so that the fibers project forward into a lens which engages the termination member, the lens being designed to disburse the light transmitted from the fiber optic bundle in many directions for observation or display.
The patents of Plyler and Gudnestad, U.S. Pat. Nos. 3,637,284 and 3,789,485 are of secondary interest.
Anderson, U.S. Pat. No. 3,790,791, discloses a fiber optic connector assembly including a fiber optic bundle which is adapted to mate with a transducer element. The bundle is disposed within a ferrule and a connector housing is provided with a tined release clip which is adapted to operatively mate with shoulder portions of the ferrule of the fiber bundle so as to retain same within the housing. The fiber optic bundle has a flush polished end with respect to the ferrule. In essence, the Anderson patent relates to a cable system wherein a connector assembly at one end of the system converts electrical energy to light energy. Light energy is transmitted through the cable system and converted to electrical energy at a second connector system located at the other end of the system. Anderson further utilizes a separate lens between his active device and the fiber optic termination. Disadvantageously, however, Anderson's transducer is a quasi-permanent portion of his optoelectronic cable assembly making replacement thereof difficult to obtain.
Mathe, U.S. Pat. No. 3,790,923, relates to an electrical connector having improved panel mounting means and an improved releasable contact construction. Mathe is concerned, inter alia, with connecting one set of electrical wires to another set of electrical wires; no mention is made by Mathe, however, of electrical-optical transmission.
Kaelin, U.S. Pat. No. 3,792,284, discloses a fiber optic connector assembly wherein the forward end of a fiber optic bundle is disposed within a sleeve in such a manner that the forward end is recessed within the sleeve and a transducer is disposed within the forward end of the sleeve so as to abut and mate with the bundle. Kaelin describes a unitary coupling device which provides structure which permanently positions and secures the light passing end of a fiber optic light guide and a photoelectric transducing element inside a sealed enclosure with electrical connectors from the transducing element to the outside. Once established, the interface between the light passing end of the light guide and the photoelectric transducing element remains undisturbed.
As further background of prior art believed to be pertinent, the following paragraphs are quoted verbatim from column 1, lines 9 to 38, of Kaelin:
"For certain applications it is desirable to transmit signals between two units of a system over a closed nonconductive nonelectrical transmission path. Such a path may be provided by a light pipe employing a flexible fiber optic light guide. Electrical signals are converted to light signals in one unit of the system and the light signals are transmitted by way of the fiber optic light guide to a second unit where they are reconverted to electrical signals. Thus, the two units of the system can be completely electrically isolated from each other and no electrical interference can affect the signals conducted over the optical transmission path." PA1 "In a system of the foregoing type the ends of the fiber optic light guide must be properly positioned with respect to photo-electric transducing elements, a light source in the first unit and a photosensitive element in the second unit. Heretofore the usual practice has been to assemble the photo-electric transducing elements within the units between which the signals are to be sent, and then attach the fiber optic light guide to the units with the ends in light transmitting-receiving relationship with the photo-electric transducing elements. That is, optical connections were made between the fiber optic light guide and the units of the system. However, each reconnection of the fiber optic light guide to either of the units required careful physical adjustment in order to obtain proper coupling between the end of the light guide and the photo-electric transducing element, and care was necessary to avoid the presence of foreign matter between this interface."
To provide emphasis, as set forth above by Kaelin, a prior art problem of each reconnection of the fiber optic light guide to either of the photo-electric transducing elements required careful physical adjustment in order to obtain proper coupling between the end of the light guide and the photo-electric transducing element.
Clanton, U.S. Pat. No. 3,809,908, relates to an electro-optical transmission line for use in an interconnection system wherein an electrical signal is converted to an optical output signal by a light emitting diode. The optical light signal is transmitted by an optical fiber bundle to a light receiving diode which converts the optical signal back to an electrical signal. The optical bundle is terminated at its ends with coaxial electrical contact assemblies which mount the diodes. The contact assemblies may be mounted in standard electrical connector members. The electro-optical transmission line of Clanton has an electrical input and an electrical output, the conversion to and from light energy being performed within the connector members integrally associated with his transmission line.
Love, U.S. Pat. No. 3,846,010, describes an optical wave guide connector for joining two bundles of optical wave guides together so that corresponding fibers of the bundles mate with each other. Generally, fiber bundles are held by hexagonal or triangular shaped ferrules, the protruding fiber ends are cut off with a diamond saw and ground down with grinding paper. The ferrules are joined together with an alignment sleeve and index matching fluid is inserted between the ends of the fibers of the two bundles to eliminate insertion losses due to Fresnel reflections. Due to its geometry, the hexagonal ferrule can house, 7, 19, 37, 61, 91, 127, etc. fibers; the triangular ferrule can house 3, 6, 10, 15, 21, 28, 36, 45, etc. fibers.
The Du Pont Company publication "Designing with Du Pont Crofon Fiber Optics" suggests that Crofon light guides or optical fibers may be cut to length with a sharp razor blade, a guillotine type cutter, or a rotary knife. The Du Pont publication states that lenses can be used to collect more light at the input end of a light guide, and that lenses can be used at the output end of the light guide for increasing light intensity or to enlarge the light cone for broader visability.
In the prior art, it is noted that the term "fiber optic wave guide" and the term "fiber optic light guide" is used interchangeably. The term "fiber optic light guide" is used throughout the specification merely as a preference of usage, and is not meant to exclude the application of such guides outside of the visible light spectrum.
As a practical matter, electrical optical connectors are normally used in clean environments, such as office buildings and the like, wherein dirt and other foreign matter is not a problem in the reconnection of such connector parts. Typically, such electrical and optical connections are not made out-of-doors, near mud, dirt, sand, and other similar environments where foreign matter is a concern.